Noisy Iterated Prisoner's Dilemma

Tit-For-Whoops

Inspired by a strategy from ncase.me/trust

def tit_for_whoops(m, t, s):
    if len(t) < 2:
        return 'c'
    else:
        return 'd' if all([x == 'd' for x in t[-2:]]) else 'c'

Defects only if the other player has defected twice in a row, to prevent misunderstandings.

Change of Heart

def change_of_heart(m, t, s):
    return 'c' if len(t) < 180 else 'd'

Has a change of heart partway through. Does surprisingly well.

Strategy Stealer

Inspired by enough, change_of_heart, and tit-for-whoops. Should be a little more forgiving. I tried to tweak the numbers for best results but they didn't want to change much.

def stealer(mine, theirs, state):
    if len(mine) == 0:
        state.append('c')
        return 'c'
    elif len(mine) > 250:
        return "d"
    elif state[0] == 't':
        return 'd'
    elif mine[-40:].count('d') > 10:
        state[0] = 't'
        return 'd'
    elif theirs[-1] == 'd':
        if state[0] == 'd':
            state[0] = 'c'
            return 'd'
        else:
            state[0] = 'd'
            return 'c'
    elif all([x == 'c' for x in theirs[-3:]]):
        state[0] = 'c'
        return 'c'
    else:
        return 'c'